WO2023085010A1

WO2023085010A1 - Light-emitting device and image display device

Info

Publication number: WO2023085010A1
Application number: PCT/JP2022/038786
Authority: WO
Inventors: 幹夫滝口
Original assignee: ソニーグループ株式会社
Priority date: 2021-11-12
Filing date: 2022-10-18
Publication date: 2023-05-19

Abstract

A light-emitting device according to one embodiment of the present disclosure comprises: a light source unit that has a light emission surface and emits first light from the light emission surface; and a wavelength conversion layer that is positioned on the light emission surface-side of the light source unit, has a first surface positioned facing the light emission surface and a second surface on the reverse side from the first surface, and includes a plurality of wavelength conversion materials and a plurality of scattering particles for converting the first light into second light in a different wavelength band, the absorption coefficient of the first light in the vicinity of the first surface being lower than the absorption coefficient of the first light in the vicinity of the second surface.

Description

Light-emitting device and image display device

The present disclosure relates to a light-emitting device and an image display device including the same.

For example, in Patent Document 1, a first resin layer in which only a light scattering material is dispersed on a light emitting diode (LED) element and a second resin layer in which a light scattering material and quantum dots are dispersed are laminated in this order. An LED device is disclosed that includes a wavelength converting member that is coated with a layer.

JP 2020-43353 A

By the way, light-emitting devices using quantum dots as wavelength conversion materials are required to have both light extraction efficiency and reliability.

It is desirable to provide a light-emitting device and an image display device capable of achieving both light extraction efficiency and reliability.

A light-emitting device according to an embodiment of the present disclosure includes a light-emitting surface, a light source section that emits first light from the light-emitting surface, and a light-emitting surface side of the light source section that faces the light-emitting surface. a plurality of wavelength-converting materials and a plurality of scatterers for converting first light into second light having a different wavelength band and having a first surface and a second surface opposite the first surface; and a wavelength conversion layer containing particles, wherein the absorption coefficient of the first light in the vicinity of the first surface is lower than the absorption coefficient of the first light in the vicinity of the second surface.

An image display device according to an embodiment of the present disclosure includes the light emitting device according to the above embodiment.

In the light emitting device of one embodiment of the present disclosure and the image display device of one embodiment, a plurality of wavelength conversion materials for converting first light emitted from the light source unit into second light having a different wavelength band, and a plurality of scattering In the wavelength conversion layer, the absorption coefficient of the first light in the vicinity of the light source side surface (first surface) is lower than the absorption coefficient of the first light in the vicinity of the light extraction surface (second surface). I made it so that This reduces the absorptance of the excitation light in the vicinity of the light source.

It is a cross-sectional schematic diagram showing an example of a configuration of a light-emitting device according to an embodiment of the present disclosure. 3 is a characteristic diagram showing simulation results of the relationship between the thickness of a QD layer that does not contain scattering particles and the light extraction efficiency in Example and Comparative Examples 1 and 2. FIG. FIG. 5 is a characteristic diagram showing simulation results of the relationship between the position in the wavelength conversion layer and the amount of excitation light absorbed per unit length in Example and Comparative Examples 1 and 2; FIG. 2 is a schematic cross-sectional view showing an example of a configuration of a light-emitting unit including a plurality of light-emitting devices shown in FIG. 1; 2 is a schematic cross-sectional view showing another example of the configuration of a light-emitting unit including a plurality of light-emitting devices shown in FIG. 1. FIG. It is a cross-sectional schematic diagram showing an example of a configuration of a light-emitting device according to Modification 1 of the present disclosure. FIG. 10 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 2 of the present disclosure; FIG. 10 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 3 of the present disclosure; It is a cross-sectional schematic diagram showing an example of a structure of quantum dot fluorescent substance. FIG. 10 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 4 of the present disclosure; FIG. 11 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 5 of the present disclosure; FIG. 11 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 6 of the present disclosure; FIG. 12 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 7 of the present disclosure; FIG. 12 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 8 of the present disclosure; FIG. 21 is a schematic cross-sectional view showing an example of a configuration of a light-emitting unit according to Modification 9 of the present disclosure; FIG. 20 is a schematic cross-sectional view showing an example of a configuration of a light-emitting unit according to Modification 10 of the present disclosure; FIG. 21 is a schematic cross-sectional view showing an example of a configuration of a light-emitting unit according to Modification 11 of the present disclosure; FIG. 12 is a cross-sectional schematic diagram showing an example of a cross-sectional configuration of a wavelength conversion layer according to Modification 12 of the present disclosure. FIG. 21 is a schematic cross-sectional view showing an example of a configuration of a light-emitting device according to Modification 13 of the present disclosure; 1 is a perspective view showing an example of a configuration of an image display device according to Application Example 1 of the present disclosure; FIG. 21 is a schematic diagram showing an example of the layout of the image display device shown in FIG. 20; FIG. It is a pixel circuit diagram of an active matrix drive system. FIG. 11 is a perspective view showing an example of a configuration of an image display device according to Application Example 2 of the present disclosure; 24 is a perspective view showing the configuration of the mounting board shown in FIG. 23; FIG. 25 is a perspective view showing the configuration of the unit board shown in FIG. 24; FIG. FIG. 11 is a diagram illustrating an example of an image display device according to Application Example 3 of the present disclosure;

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspects. In addition, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of explanation is as follows.
1. Embodiment (example of light-emitting device in which scattering particles are selectively dispersed on the light extraction surface side)
1-1. Configuration of Light Emitting Device 1-2. Configuration of Light Emitting Unit 1-3. Action and effect 2. Modified example 1 (an example in which the concentration of scattering particles is changed between the light source side and the light extraction surface side)
3. Modified example 2 (an example in which the concentration of the quantum dot phosphor is changed between the light source side and the light extraction surface side)
4. Modified example 3 (an example in which the configuration of the quantum dot phosphor is changed between the light source side and the light extraction surface side)
5. Modified example 4 (an example in which a resin layer is provided between the light source side and the light extraction surface side)
6. Modification 5 (an example in which a region containing only scattering particles is provided on the light source side)
7. Modification 6 (example using Cd-based quantum dot phosphor and Cd-free quantum dot phosphor)
8. Modified example 7 (an example in which the concentration of scattering particles in the in-plane direction is changed on the light extraction surface side)
9. Modification 8 (example in which the side surface of the wavelength conversion layer is inclined)
10. Modification 9 (Example of a light-emitting unit in which a microlens array is arranged on the light extraction surface)
11. Modification 10 (Another example of the configuration of the wavelength conversion layer of the blue light emitting device)
12. Modification 11 (Example of light-emitting unit in which color filters are arranged on the light extraction surface)
13. Modification 12 (another example of the structure of the wavelength conversion layer)
14. Modified Example 13 (example in which a textured structure is arranged on the light extraction surface)
15. Application example

<1. Embodiment>
FIG. 1 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 1) according to an embodiment of the present disclosure. The light-emitting device 1 is preferably used, for example, in the display pixels P of an image display device (eg, image display device 100, see FIG. 20).

The light emitting device 1 of the present embodiment includes a light source unit 10 that emits excitation light EL, and a light emitting surface (surface 10S2) of the light source unit 10. The light emitting device 1 absorbs the excitation light EL and emits light of a different wavelength. and a wavelength conversion layer 20 that The wavelength conversion layer 20 has, for example, a plurality of quantum dot phosphors 21 and a plurality of scattering particles 22 dispersed in a resin 23. The first region 20A and the second region are arranged in order from the surface 10S2 side of the light source unit 10. 20B. The first region 20A has a configuration in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23, and has a lower absorption coefficient of the excitation light EL than the second region 20B.

(1-1. Configuration of Light Emitting Device)
The light source section 10 corresponds to a specific example of the "light source section" of the present disclosure. The light source unit 10 is a solid-state light-emitting device that emits light in a predetermined wavelength band from its upper surface (light-emitting surface), such as a light-emitting diode (LED) chip. An LED chip refers to a chip cut out from a wafer used for crystal growth, not a package type covered with molded resin or the like. The LED chip has a size of, for example, 1 μm or more and 100 μm or less, and is called a micro LED.

The light source section 10 has a first conductivity type layer 11, an active layer 12 and a second conductivity type layer 13 laminated in this order. The upper surface of the second conductivity type layer 13 is a light exit surface. The light source unit 10 has a columnar mesa portion M including a first conductivity type layer 11 and an active layer 12, and the first conductivity type layer 11 is exposed on the surface (surface 10S1) opposite to the light emitting surface. It has a step formed by a convex portion and a concave portion exposing the second conductivity type layer 13 . In the present embodiment, the surface opposite to the light extraction surface 10S2 (the surface 10S1 side) including the projections and recesses is the lower surface. The light source unit 10 further includes a first electrode 14 electrically connected to the first conductivity type layer 11 and a second electrode 15 electrically connected to the second conductivity type layer 13 . The first electrode 14 and the second electrode 15 are each provided on the surface 10S1 side. Specifically, the first electrode 14 is arranged on the surface 10S1 of the first conductivity type layer, which is the convex portion on the lower surface, and the second electrode 15 is arranged on the surface 10S1 of the second conductivity type layer, which is the concave portion on the lower surface. are placed in

The side surface of the light source section 10 made up of the first conductive layer 11, the active layer 12 and the second conductive layer 13 is covered with a laminated film 16 made up of an insulating film 16A and a reflective film 16B. The laminated film 16 extends, for example, to the periphery of the first electrode 14 and the second electrode 15, and has openings 16H1 and 16H2 on the first electrode 14 and the second electrode 15, respectively. That is, the first electrode and the second electrode are exposed to the outside through the openings 16H1 and 16H2, respectively.

The materials forming the first conductivity type layer 11, the active layer 12 and the second conductivity type layer 13 are appropriately selected according to the desired wavelength band of light. For example, when a III-V group compound semiconductor material is used, the light source unit 10 may emit ultraviolet light having an emission wavelength of 360 nm or more and 430 nm or less, or blue band light having an emission wavelength of 430 nm or more and 500 nm or less (blue light ). Examples of Group III-V compound semiconductor materials include AlGaInN-based materials. In addition, a ZnSe-based material or a ZnO-based material may be used. The active layer 12 can be formed using, for example, a GaInN-based material.

The light emitted from the light source unit 10 is not limited to ultraviolet light or blue light, and may be, for example, infrared light or red band light (red light). In that case, examples of III-V group compound semiconductor materials that emit infrared rays include AlGaInAs-based materials. Examples of III-V group compound semiconductor materials that emit red light include AlGaInP-based materials.

The first electrode 14 is in contact with the first conductivity type layer 11 and is electrically connected to the first conductivity type layer 11 . That is, the first electrode 14 is in ohmic contact with the first conductivity type layer 11 . The first electrode 14 is, for example, a metal electrode, and is configured, for example, as a multilayer film (Ni/Au) of nickel (Ni) and gold (Au). Alternatively, the first electrode 14 may be made of a transparent conductive material such as indium tin oxide (ITO).

The second electrode 15 is in contact with the second conductivity type layer 13 and is electrically connected to the second conductivity type layer 13 . That is, the second electrode 15 is in ohmic contact with the second conductivity type layer 13 . The second electrode 15 is, for example, a metal electrode, and is configured as, for example, a multilayer film (Ti/Al) of titanium (Ti) and aluminum (Al) or a multilayer film of chromium (Cr) and Au (Cr/Au). It is Alternatively, the second electrode 15 may be made of a transparent conductive material such as ITO.

The laminated film 16 is formed from the side surface to the bottom surface of the light source section 10 as described above. The insulating film 16A and the reflective film 16B are thin films, respectively, and can be formed by thin film forming processes such as CVD, vapor deposition, and sputtering, for example.

The insulating film 16A is for electrical insulation between the reflective film 16B and the first conductivity type layer 11, the active layer 12 and the second conductivity type layer 13. As shown in FIG. The insulating film 16A is preferably formed using a material transparent to light emitted from the active layer 12. As shown in FIG. Such materials include, for example, SiO ₂ , Si ₂ N ₃ , Al ₂ O ₃ , TiO ₂ and TiN. The thickness of the insulating film 16A is, for example, approximately 50 nm to 1 μm.

The reflective film 16B is for reflecting the light emitted from the active layer 122. The reflective film 16B is provided with the insulating film 16A interposed therebetween. Specifically, the reflective film 16B extends to the side surface and the lower surface of the light source unit 10, and is formed in the openings 16H1 and 16H2 of the insulating film 16A, for example, to a position slightly recessed from the end of the insulating film 16A. there is Thereby, the reflective film 16B is insulated (electrically separated) from the first conductive layer 11, the active layer 12, the second conductive layer 13, the first electrode 14, and the second electrode 15 by the insulating film 16A. . As a material for the reflective film 16B, it is preferable to use a material that reflects the light emitted from the active layer 12 to form it. Such materials include, for example, Ti, Al, silver (Ag), copper (Cu), Au, Ni, or alloys thereof. The thickness of the reflective film 16B is, for example, about 50 nm to 1 μm.

An insulating film may be further formed on the reflective film 16B. In that case, the insulating film is preferably formed on the first electrode 14 and the second electrode 15 up to the insulating film 16A so as to cover the end portion of the reflective film 16B. As a result, when the light emitting device 1 (1B, 1G, 1R) described later is mounted on the drive substrate 41, the

pad electrodes

42, 43 on the drive substrate 41 and the first electrode 14 and the second electrode 15 are joined together. It is possible to prevent a short circuit between the

bumps

44 and 45 and the reflective film 16B (see FIG. 4).

The wavelength conversion layer 20 corresponds to a specific example of the "wavelength conversion layer" of the present disclosure. The wavelength conversion layer 20 is arranged on the surface 10S2 side of the light source unit 10, and converts the light emitted from the light source unit 10 into light of a desired wavelength band (eg, red light Lr, green light Lg, and blue light Lb). It is. The wavelength conversion layer 20 has a surface 20S1 and a surface 20S2 as a pair of surfaces facing each other. The surface 20S1 corresponds to the “first surface” of the present disclosure, and is arranged to face the surface 10S2 of the light source section 10 . The surface 20S2 corresponds to the “second surface” of the present disclosure, and serves as an extraction surface for wavelength-converted light.

In the wavelength conversion layer 20, a plurality of quantum dot phosphors 21 and a plurality of scattering particles 22 are dispersed in the resin 23 as described above.

The quantum dot phosphor 21 corresponds to a specific example of the "wavelength conversion material" of the present disclosure. The quantum dot phosphor 21 absorbs the light emitted from the light source section 10 as excitation light EL and emits fluorescence. Specifically, the quantum dot phosphor 21 is, for example, a particulate phosphor that emits fluorescence in a blue wavelength band of 430 nm or more and 500 nm or less, a green wavelength band of 500 nm or more and 550 nm or less, or a red wavelength band of 610 nm or more and 780 nm or less. be.

The most significant factor that determines the fluorescence wavelength (fluorescence color) of quantum dot phosphors is the bandgap energy of the material that constitutes the quantum dots. Therefore, it is desirable to select the material according to the desired fluorescent color. For example, when obtaining red fluorescence (red light Lr), the quantum dot phosphor 21 can be selected from InP, GaInP, InAsP, CdSe, CdZnSe, CdTeSe, CdTe, or the like. When obtaining green fluorescence (green light Lg), the quantum dot phosphor 21 can be selected from, for example, InP, GaInP, ZnSeTe, ZnTe, CdSe, CdZnSe, CdS, CdSeS, and the like. When obtaining blue fluorescence (blue light Lb), the quantum dot phosphor 21 can be selected from ZnSe, ZnTe, ZnSeTe, CdSe, CdZnSe, CdS, CdZnS, CdSeS, and the like. In addition, the quantum dot phosphor 21 is not limited to the above, and for example, CuInSe ₂ , CuInS ₂ , CuInGaS, AgInS ₂ or the like may be used. In addition, for example, perovskite nanophosphors composed of CsPb(Cl/Br) ₃ , CsPbBr ₃ , CsPb(I/Br) ₃ and CsPbI ₃ may be used.

In addition, the quantum dot phosphor 21 can also control the fluorescent color by its particle size. For example, the smaller the particle size, the shorter the fluorescence wavelength. In order to obtain fluorescence with high color purity, it is desirable to select a quantum dot phosphor whose particle size is controlled.

The quantum dot phosphor 21 has an average particle size of, for example, 5 nm or more and 100 nm or less, and has a core/shell structure consisting of a core that emits light with an average particle size of about 2 nm to 10 nm, and a shell that covers and protects the core. . The shell consists of one layer or multiple layers. The shell may further be covered with _an inorganic film such as silicon oxide ( _SiO2 ) or aluminum oxide ( _Al2O3 ). A large number of organic ligands are coordinated to the surface of the quantum dot phosphor 21, and the organic ligands cause aggregation of the quantum dot phosphor 21 when the quantum dot phosphor and the solvent are mixed. is suppressed and the dispersibility is improved.

For filling the quantum dot phosphors 21, for example, an inkjet or needle dispenser that ejects or applies the resin 23 mixed with the quantum dot phosphors 21 depending on the viscosity is used. This is classified as a plateless printing method, and in the above method, it is possible to selectively fill the quantum dot phosphor 21 only in the barrier, so the utilization efficiency of the quantum dot phosphor 21 can be improved. . You may make it apply|coat the quantum dot fluorescent substance 21 to the place determined using the screen printing which is a plate-type printing method, or gravure printing technology. Alternatively, the quantum dot phosphor 21 may be applied to the entire base material by a spin coater, a PR method, or the like.

In the wavelength conversion layer 20, in addition to the quantum dot phosphor 21, an inorganic phosphor or an organic phosphor may be used as the wavelength conversion material.

The scattering particles 22 scatter the excitation light EL emitted from the light source unit 10 and the fluorescence emitted from the quantum dot phosphor 21 to change the incident angle of the fluorescence to the light extraction surface 20S2, thereby improving the light extraction efficiency. It is for The scattering particles 22 are for increasing the effective optical path length of the excitation light EL, thereby improving the absorption rate of the excitation light EL. It is preferable that the scattering particles 22 have an average particle size larger than that of the quantum dot phosphor 21 and a refractive index larger than that of the resin 23 . For the scattering particles 22, it is preferable to use a dielectric substance having a particle size of, for example, 100 nm or more and 1000 nm or less. Specific materials of the scattering particles 22 include, for example, silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN) and zinc oxide. (ZnO) and the like.

The scattering particles 22 may be, for example, air bubbles mixed in the filler 123 or aggregated quantum dot phosphors 21 .

The resin 23 is for dispersing the quantum dot phosphors 21 and the scattering particles 22, and can be formed using, for example, a material having optical transparency to the excitation light EL. As a specific material of the resin 23, for example, an ultraviolet curable resin or a thermosetting resin can be used. Specifically, polypropylene, polyethylene, polystyrene, AS resin, ABS resin, methacrylic resin, polyvinyl chloride, polyacetal, polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene Sulfide, polyamideimide, polymethylpentene, liquid crystal polymer, epoxy resin, acrylic resin, phenolic resin, urea resin, melanin resin, diallyl phthalate resin, unsaturated polyester resin, polyimide, polyurethane and silicone resin or mixtures thereof. In addition, sol-gel glass or the like may be used.

The resin 23 is not necessarily required, and the quantum dot phosphor 21 and the scattering particles 22 may be enclosed in the hollow structure.

In the present embodiment, the wavelength conversion layer 20 has a first region 20A and a second region 20B that have different absorption coefficients for the excitation light EL in order from the surface 10S2 side of the light source section 10 . The first region 20</b>A does not include the plurality of scattering particles 22 in the resin 23 and has a configuration in which only the plurality of quantum dot phosphors 21 are dispersed. The second region 20</b>B has a configuration in which both the multiple quantum dot phosphors 21 and the multiple scattering particles 22 are dispersed in the resin 23 . Accordingly, the first region 20A has a lower absorption coefficient of the excitation light EL than the second region 20B.

FIG. 2 shows simulation results of the relationship between the thickness of the QD layer (wavelength conversion layer 20) that does not contain the scattering particles 22 and the light extraction efficiency in Example and Comparative Examples 1 and 2. FIG. 3 shows simulation results of the relationship between the position in the wavelength conversion layer 20 and the amount of excitation light absorbed per unit length in Example and Comparative Examples 1 and 2. As shown in FIG. An example is a light-emitting device 1 having the above configuration. Comparative Example 1 is a light-emitting device in which a plurality of quantum dot phosphors 21 and a plurality of scattering particles are dispersed substantially uniformly throughout the resin 23 forming the wavelength conversion layer 20 . Comparative Example 2 is a light-emitting device in which only the plurality of quantum dot phosphors 21 are substantially uniformly dispersed throughout the resin 23 forming the wavelength conversion layer 20 without including the plurality of scattering particles 22 .

The excitation light EL incident on the wavelength conversion layer 20 is scattered by the scattering particles 22 to increase the optical path length. As a result, the wavelength conversion layer 20 (Example and Comparative Example 2) in which the plurality of scattering particles 22 are dispersed together with the plurality of quantum dot phosphors 21 does not contain the plurality of scattering particles 22 (Comparative Example 2). In comparison, the absorption rate of the excitation light EL in the wavelength conversion layer 20 increases. Further, the fluorescence emitted from the quantum dot phosphor 21 is scattered by the scattering particles 22, thereby improving the light extraction efficiency (FIG. 2). On the other hand, as the optical path length of the excitation light EL in the wavelength conversion layer 20 increases, the temperature of the wavelength conversion layer 20 rises due to the heat generated by the quantum dot phosphors 21 due to the absorption of the excitation light EL. deterioration is more likely to occur. The heat generation of the quantum dot phosphor 21 due to the absorption of the excitation light EL becomes remarkable in the vicinity of the light source section 10 .

On the other hand, in the embodiment, the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed without including the plurality of scattering particles 22 in the resin 23 is provided on the light source unit 10 side. As a result, the light density in the vicinity of the light source section 10 side is reduced, and the absorption amount of the excitation light EL per unit length is reduced to approximately the same level as in Comparative Example 2 (FIG. 3). Therefore, temperature rise in the vicinity of the light source unit 10 is suppressed, and deterioration of the quantum dot phosphor 21 is reduced.

A side surface (surface 20S3) of the wavelength conversion layer 20 is sealed by a side wall 24, for example. Examples of materials forming the sidewall 24 include SiO ₂ , silicon (Si), resist, resin, and metal materials such as Cu and Al.

A light reflecting film 25 may be formed between the wavelength conversion layer 20 and the sidewall 24 . The light reflecting film 25 is for reflecting the excitation light EL emitted from the light source unit 10 and scattered by the scattering particles 22 and fluorescence emitted from the quantum dot phosphor 21 into the wavelength conversion layer 20. . The light reflecting film 25 is preferably formed using a material that has a high reflectance with respect to the excitation light EL and fluorescence regardless of the light incident angle. Examples of materials for the light reflecting _film 25 include metal materials such as gold (Au), _Ag , aluminum (Al ₎ and platinum (Pt ₎ _; A dielectric multilayer film in which ₂ O ₃ is combined is exemplified.

(1-2. Structure of Light Emitting Unit)
In the image display device 100, which will be described later, a plurality of display pixels P are arranged in a two-dimensional array in the display area 100A. A light-emitting unit 2 including a plurality of light-emitting devices 1 is arranged in each of the plurality of display pixels P. As shown in FIG. FIG. 4 schematically shows a cross-sectional configuration of the light emitting unit 2. As shown in FIG.

The light-emitting unit 2 is, for example, a plurality of light-emitting devices 1 arranged in a row. The light emitting unit 2 has, for example, an elongated shape extending in the arrangement direction of the plurality of light emitting devices 1 .

For example, the display pixels P of the image display device 100 include, for example, three color pixels Pr, Pg, and Pb corresponding to RGB, and the color pixels Pr, Pg, and Pb respectively emit light in corresponding wavelength bands. A light emitting device 1 is provided. FIG. 4 schematically shows an example of the cross-sectional configuration of the light emitting unit 2. As shown in FIG. The light-emitting unit 2 is composed of light-emitting

devices

1R, 1G, and 1B that emit light corresponding to respective color pixels Pr, Pg, and Pb. That is, the color pixel Pr has a light emitting device 1R that emits light in the red band (red light Lr), the color pixel Pg has a light emitting device 1G that emits light in the green band (green light Lg), and the color pixel Pb has a light emitting device 1G that emits light in the green band (green light Lg). A light-emitting device 1B that emits light in the band (blue light Lb) is provided. For example, when the light-emitting unit 2 has an elongated shape extending in the arrangement direction of the light-emitting devices 1, the light-emitting device 1R is arranged, for example, near the short side of the light-emitting unit 2, and the light-emitting device 1B is arranged, for example, , near a short side of the light emitting unit 2 that is different from the adjacent short side of the light emitting device 1B. The light emitting device 1G is arranged, for example, between the light emitting device 1R and the light emitting device 1B. The positions of the

light emitting devices

1R, 1G, and 1B are not limited to the above.

The

light emitting devices

1R, 1G and 1B are mounted on the driving substrate 41 via

pad electrodes

42 and 43 and bumps 44 and 45, respectively. It should be noted that other bonding methods such as Cu—Cu bonding may be used for mounting on the drive substrate 41 .

Each of the

light emitting devices

1R, 1G, and 1B includes, for example, a plurality of quantum dot phosphors 21 for wavelength-converting the excitation light EL into light in a predetermined wavelength band on the light source unit 10 that emits blue light as the excitation light EL. A conversion layer 20 is arranged. For example, in the wavelength conversion layer 20 of the light emitting device 1R, a plurality of quantum dot phosphors 21 that emit red fluorescence and a plurality of scattering particles 22 are dispersed in the resin 23, and the excitation emitted from the light source unit 10 The light EL is converted into red light by the quantum dot phosphor 21 and scattered by the scattering particles 22 to be taken out as red light Lr. In the wavelength conversion layer 20 of the light emitting device 1G, a plurality of quantum dot phosphors 21 emitting green fluorescence and a plurality of scattering particles 22 are dispersed in a resin 23, and the excitation light EL emitted from the light source unit 10 is converted into green light by the quantum dot phosphor 21 and scattered by the scattering particles 22 to be taken out as green light Lg. In the wavelength conversion layer 20 arranged in the light emitting device 1B, for example, only the scattering particles 22 are dispersed in the resin 23, and the excitation light EL emitted from the light source section 10 is scattered by the scattering particles 22 and becomes blue light. Taken out as Lb.

Also, an excitation light reflection film 31 may be provided as a wavelength selection layer for selectively reflecting the excitation light EL on the wavelength conversion layer 20 of the

light emitting devices

1R and 1G. As a result, the excitation light EL emitted from the light extraction surface 20S2 of the wavelength conversion layer 20 is reduced, and the color gamut can be improved. Moreover, the contrast of external light can be improved. Instead of the excitation light reflecting film 31, a yellow filter that selectively absorbs blue light may be arranged.

When the light source unit 10 that emits ultraviolet rays is used as the excitation light EL, for example, as shown in FIG. A wavelength conversion layer 20 in which a quantum dot phosphor 21 and a plurality of scattering particles 22 are dispersed in a resin 23 is arranged. As a result, the excitation light EL emitted from the light source section 10 in the light emitting device 1B is converted into blue light by the quantum dot phosphor 21 and scattered by the scattering particles 22 to be extracted as blue light Lb. When the light source unit 10 that emits ultraviolet rays is used as the excitation light EL, the excitation light reflection film 31 is also arranged on the light emitting device 1B.

(1-3. Action and effect)
In the light-emitting device 1 of the present embodiment, the wavelength conversion layer 20 has the first region 20A and the second region 20B from the light source section 10 side, and the first region 20A contains only the plurality of quantum dot phosphors 21 in the resin 23. Both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed in the resin 23 in the second region 20B, and the first region 20A has a lower absorption of the excitation light EL than the second region 20B. coefficient. This reduces the absorption rate of the excitation light EL in the vicinity of the light source unit 10 . This will be explained below.

In recent years, in order to increase the color gamut of LCD TVs, products using QD sheets for backlight units have been commercialized. In addition, a display device for augmented reality (AR) applications has been developed that combines a blue LED array with a color conversion layer using quantum dots (QDs). In the color conversion layer using these QDs, a QD layer with high color conversion efficiency is required in order to increase luminance and reduce power consumption. As for the color conversion efficiency of the QD layer, in addition to the quantum yield of the QD, the light extraction efficiency from the QD layer is also important. For example, since the fluorescence emitted from the QDs emits isotropic light, the total reflection of the high-angle component at the interface between the QDs and the air reduces the amount of fluorescence extracted into the air.

To solve this problem, a method of adding scatterers to the QD layer is used. As a result, by changing the angle of fluorescence, the effect of total reflection at the interface between the QDs and air is reduced, and the light extraction efficiency is improved. In addition to this, the addition of the scatterer also increases the optical path length of the excitation light in the QD layer, thereby providing the advantage of increasing the absorption rate of the excitation light. Accordingly, by adding a scatterer to the QD layer, the color conversion efficiency of the QD layer can be improved.

On the other hand, there are also problems due to the addition of scatterers. As the optical path length of the excitation light increases, the density of the excitation light in the QD layer increases, resulting in a decrease in reliability. The reliability of the QD layer decreases as the excitation light density and the temperature of the QD layer increase. The intensity distribution of the excitation light in the QD layer, with or without scatterers, decays exponentially with distance from the LED, so the light density is highest near the LED. Further, even when the excitation light absorptivity is the same, the total amount of absorbed excitation light increases as the intensity of the excitation light increases. For this reason, heat generation due to energy loss during color conversion in the vicinity of the LEDs increases. For these reasons, the region of the QD layer near the LED has the highest light density and the highest temperature, resulting in greater degradation of the QDs. Since the excitation light absorptance in the vicinity of the LED becomes higher in the presence of the scatterer, the temperature of the QD layer in the vicinity of the LED becomes higher and the reliability deteriorates. The attained luminance of a light-emitting element using a color conversion layer of QDs is often rate-determined by reliability. For this reason, in order to improve the luminance of a light-emitting device, it becomes a challenge to achieve both light extraction efficiency and reliability of the device structure.

On the other hand, as described above, an LED device has been proposed in which a layer (scatterer layer) to which only scatterers are added is added between the LED and the QD layer to which scatterers are added. In this method, the scatterer between the LED and the QD layer makes the excitation light uniform in the lateral direction, and the distance between the LED and the QD layer increases the area of the excitation light, thereby improving reliability. Let On the other hand, the scatterer layer causes the excitation light to return from the LED to the inside of the LED, thereby reducing the amount of light incident on the QD layer, thereby reducing the light extraction efficiency of the combined LED and color conversion layer. In addition, when a narrow pitch is required as in AR applications, the angle of the QD sidewalls becomes vertical, which limits the effect of reducing the light density by increasing the distance between the LED and the QD.

On the other hand, in the present embodiment, in the wavelength conversion layer 20, the first region 20A is provided by dispersing only the plurality of quantum dot phosphors 21 in the resin 23 on the light source section 10 side, and the resin 23 is provided on the light extraction surface 20S2 side. A second region 20B is provided in which both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed. As a result, the absorption coefficient of the excitation light EL in the vicinity of the light source section 10 becomes lower than the absorption coefficient of the excitation light EL in the vicinity of the light extraction surface 20S2, and the absorption rate of the excitation light EL in the vicinity of the light source section 10 is reduced. That is, heat generation in the vicinity of the light source section 10 is reduced, and deterioration of the quantum dot phosphor 21 is reduced.

As described above, in the light-emitting device 1 of the present embodiment, it is possible to achieve both an improvement in light extraction efficiency and an improvement in reliability.

Next, modifications 1 to 13 of the present disclosure will be described. Components corresponding to those of the light-emitting device 1 of the above-described embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

<2. Modification 1>
FIG. 6 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 3) according to Modification 1 of the present disclosure. This light-emitting device 3, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

In the above-described embodiment, only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 in the first region 20A on the light source unit 10 side, and the absorption coefficient of the excitation light EL in the vicinity of the light source unit 10 is changed to the excitation light EL in the vicinity of the light extraction surface 20S2. An example in which the absorption coefficient is lower than the absorption coefficient of the optical EL is shown, but the present invention is not limited to this. For example, a plurality of scattering particles 22 may be dispersed in the first region 20A at a concentration lower than the concentration of the plurality of scattering particles in the second region 20B.

Thus, in this modification, both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed in the first region 20A, and the concentration of the plurality of scattering particles in the first region 20A is It was made lower than the concentration of a plurality of scattering particles. This makes it possible to obtain the same effects as those of the above-described embodiment.

<3. Modification 2>
FIG. 7 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 4) according to Modification 2 of the present disclosure. The light-emitting device 4, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

For example, the concentration of the plurality of quantum dot phosphors 21 dispersed in the first region 20A may be made lower than the concentration of the plurality of quantum dot phosphors 21 dispersed in the second region 20B.

Thus, in this modified example, the concentration of the plurality of quantum dot phosphors 21 in the first region 20A is made lower than the concentration of the plurality of scattering particles in the second region 20B. As a result, the amount of heat generated in the first region 20A is further reduced compared to the above-described embodiment, and the reliability can be further improved. Further, compared to the above embodiment, higher luminance can be achieved.

<4. Modification 3>
FIG. 8 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 5) according to Modification 3 of the present disclosure. This light-emitting device 5, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

A plurality of quantum dot phosphors 26 having a different material, composition, or core/shell structure from the plurality of quantum dot phosphors 21 dispersed in the second region 20B may be dispersed in the first region 20A. . For example, in the first region 20A, quantum dot phosphors 26 having a lower absorption coefficient of the excitation light EL than the quantum dot phosphors 21 dispersed in the second region 20B are dispersed. FIG. 9 schematically shows the cross-sectional configuration of the quantum dot phosphor 26. As shown in FIG. The absorption coefficient of the quantum dot phosphor 26 can be controlled by, for example, changing the thickness ratio of the core 261 and the shell A 262 and shell B 263 covering the core 261 .

Thus, in this modification, the quantum dot phosphors 26 having a lower absorption coefficient of the excitation light EL than the quantum dot phosphors 21 dispersed in the second region 20B are dispersed in the first region 20A. As a result, the amount of heat generated in the first region 20A is further reduced compared to the above-described embodiment, and the reliability can be further improved. Further, compared to the above embodiment, higher luminance can be achieved.

<5. Modification 4>
FIG. 10 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 6) according to Modification 4 of the present disclosure. This light-emitting device 6, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

In the above-described embodiment, only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 in the first region 20A on the light source unit 10 side, and the absorption coefficient of the excitation light EL in the vicinity of the light source unit 10 is changed to the excitation light EL in the vicinity of the light extraction surface 20S2. An example in which the absorption coefficient is lower than the absorption coefficient of the optical EL is shown, but the present invention is not limited to this. For example, between the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 and the second region 20B in which both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed , a region 20X made only of the resin 23 may be provided.

Thus, in this modification, the region 20X made only of the resin 23 is provided between the first region 20A and the second region 20B so as to spatially separate the first region 20A and the second region 20B. made it As a result, it is possible to reduce the influence of heat generation on the first region 20A with respect to the second region 20B. Therefore, the reliability can be further improved as compared with the above embodiment. Further, compared to the above embodiment, higher luminance can be achieved.

<6. Modification 5>
FIG. 11 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 7) according to Modification 5 of the present disclosure. This light-emitting device 7 is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100), like the light-emitting device 1 in the above embodiment.

In the above embodiment, the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 and the second region 20B in which both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed are provided in this order from the light source unit 10 side, but the configuration of the wavelength conversion layer 20 is not limited to this. For example, the wavelength conversion layer 20 is divided into, for example, three regions, a first region 20A, a second region 20B, and a third region 20C, from the light source unit 10 side, and the first region 20A contains only the plurality of scattering particles 22. The second region 20B and the third region 20C may have the same configurations as the first region 20A and the second region 20B of the above embodiment, respectively.

Thus, in this modification, the first region 20A, the second region 20B, and the third region 20C are divided from the light source unit 10 side, for example, into three regions, and only the plurality of scattering particles 22 are placed in the first region 20A. I tried to disperse it. As a result, the excitation light EL incident on the wavelength conversion layer 20 from the light source unit 10 is homogenized in the first region 20A, so that only the plurality of quantum dot phosphors 21 are incident on the second region 20B dispersed in the resin 23. In-plane uniformity of the excitation light EL can be improved. Therefore, the reliability can be further improved as compared with the above embodiment.

<7. Modification 6>
FIG. 12 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 8) according to Modification 6 of the present disclosure. The light-emitting device 8, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

In the above embodiment, the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 and the second region 20B in which both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed are provided in this order from the light source unit 10 side, but the configuration of the wavelength conversion layer 20 is not limited to this. For example, a third region 20C in which both the plurality of quantum dot phosphors 21B and the plurality of scattering particles 22 are dispersed may be further provided on the second region 20B of the above embodiment.

In this modification, the multiple quantum dot phosphors 21A dispersed in the first region 20A and the second region 20B are made of different materials from the multiple quantum dot phosphors 21B dispersed in the third region 20C. In general, so-called Cd-based quantum dot phosphors have higher light resistance than Cd-free quantum dot phosphors. In this modification, the Cd-based quantum dot phosphor is used for the first region 20A and the second region 20B, and the Cd-free quantum dot phosphor is used for the third region 20C.

Thus, by providing the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 in the wavelength conversion layer 20 on the light source unit 10 side, other regions (for example, the farthest from the light source unit 10) It becomes possible to use a Cd-free quantum dot phosphor for the third region 20C). Therefore, the Cd concentration in the wavelength conversion layer 20 can be reduced, and the environmental load can be reduced.

<8. Modification 7>
FIG. 13 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 9) according to Modification 7 of the present disclosure. This light-emitting device 9, like the light-emitting device 1 in the above-described embodiment, is suitably used for, for example, the display pixels P of an image display device (for example, the image display device 100).

In the above embodiment, the first region 20A in which only the plurality of quantum dot phosphors 21 are dispersed in the resin 23 and the second region 20B in which both the plurality of quantum dot phosphors 21 and the plurality of scattering particles 22 are dispersed are provided in this order from the light source unit 10 side, but the configuration of the wavelength conversion layer 20 is not limited to this. For example, as shown in FIG. 13, the first region 20A may extend toward the light extraction surface 20S2, and the first region 20A may be provided around the second region 20B.

Thus, in this modification, the concentration of the plurality of quantum dot phosphors 21 in the wavelength conversion layer 20 is also changed in the lateral direction. As a result, in plan view, the light extraction efficiency is relatively high even near the center of the light emitting device 9 . Therefore, by combining with a microlens array 32 to be described later, it is possible to improve the controllability of the light distribution characteristics of the light emitting device 9 .

<9. Modification 8>
FIG. 14 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 1) according to Modification 8 of the present disclosure. In the above embodiment, an example in which the side surface (surface 20S3) of wavelength conversion layer 20 is vertical is shown, but the present invention is not limited to this. For example, as shown in FIG. 14, the surface 20S3 of the wavelength conversion layer 20 may be an inclined surface extending from the surface 20S1 toward the surface 20S2. This makes it possible to further improve the light extraction efficiency of fluorescence emitted in the wavelength conversion layer 20 .

<10. Modification 9>
FIG. 15 schematically illustrates an example of a cross-sectional configuration of a light-emitting unit (light-emitting unit 2A) according to Modification 9 of the present disclosure. A microlens array 32 may be provided on the light extraction surface 20S2 of the

light emitting devices

1R, 1G, and 1B.

The microlens array 32 corresponds to a specific example of the "light distribution control structure" of the present disclosure. As the light distribution control structure, in addition to the microlens array 32, a photonic crystal, a moth-eye structure, a nanoantenna, and a metamaterial may be provided. This makes it possible to increase the luminance on the low-angle side, for example.

<11. Modification 10>
FIG. 16 schematically illustrates an example of a cross-sectional configuration of a light-emitting unit (light-emitting unit 2B) according to Modification 10 of the present disclosure. In the above-described embodiment, an example in which a plurality of scattering particles 22 are dispersed substantially uniformly in the wavelength conversion layer 20 arranged in the light emitting device 1B is shown, but the present invention is not limited to this. For example, similarly to the

light emitting devices

1R and 1G, the first region 20A and the second region 20B are provided, and the concentration of the plurality of scattering particles 22 in the second region 20B is higher than the concentration of the plurality of scattering particles 22 in the first region 20A. You can make it higher. This reduces the ratio of the excitation light EL returning to the light source unit 10 . Therefore, it is possible to improve the light extraction efficiency of the light emitting device 1B and reduce the power consumption.

<12. Modification 11>
FIG. 17 schematically illustrates an example of a cross-sectional configuration of a light-emitting unit (light-emitting unit 2C) according to Modification 11 of the present disclosure. In the above embodiments, the corresponding red light Lr, green light Lg, and blue light Lb are emitted from the

light emitting devices

1R, 1G, and 1B, but the present invention is not limited to this. For example, white light is emitted from each wavelength conversion layer 20 of the

light emitting devices

1R, 1G, and 1B, and corresponding color filters (red filters 33R , a green filter 33G and a blue filter 33B) may be provided. This eliminates the step of separately painting the wavelength conversion layer 20 for each of the color pixels Pr, Pg, and Pb, thus making it possible to reduce the manufacturing cost.

<13. Modification 12>
FIG. 18 schematically illustrates another example of the cross-sectional configuration of the wavelength conversion layer 20 in Modification 12 of the present disclosure. In the above-described embodiment, an example in which each light source unit 10 is partitioned by the side wall 24 is shown, but the present invention is not limited to this. For example, as shown in FIG. 18, the wavelength conversion layer 20 is made to emit white light Lw, and the top and bottom of the wavelength conversion layer 20 are sealed with, for example,

barrier films

27 and 28 having light transmittance. It is good also as the wavelength conversion layer 20 of shape. This makes it possible to provide a high-luminance QD sheet. Such a QD sheet can be used, for example, as a backlight for a liquid crystal display device.

<14. Modification 13>
FIG. 19 schematically illustrates an example of a cross-sectional configuration of a light-emitting device (light-emitting device 1) according to Modification 13 of the present disclosure. A texture structure 34 may be further provided on the light extraction surface (surface 20S2) of the wavelength conversion layer 20. FIG. As a result, of the fluorescence emitted from the wavelength conversion layer 20, the fluorescence whose angle is smaller than the critical angle while the fluorescence with the critical angle or more is repeatedly reflected in the wavelength conversion layer 20 can be extracted from the light extraction surface. Become. Therefore, in addition to the effects of the above embodiments, it is possible to achieve high luminance.

In this modified example, an example in which the texture structure 34 is separately provided on the light extraction surface (surface 20S2) of the wavelength conversion layer 20 is shown. may

<15. Application example>
(Application example 1)
FIG. 20 is a perspective view showing an example of a schematic configuration of an image display device (image display device 100). The image display device 100 is a so-called LED display, and the display pixels P use the light-emitting device (for example, the light-emitting device 1) of the present disclosure. The image display device 100 includes a display panel 110 and a control circuit 140 that controls driving of the display panel 110, as shown in FIG. 20, for example.

The display panel 110 is obtained by superimposing a mounting substrate 120 and a counter substrate 130 on each other. The surface of the counter substrate 130 serves as an image display surface, and has a display area 100A in the central portion and a frame area 100B as a non-display area around it.

FIG. 21 shows an example of the wiring layout of the area corresponding to the display area 100A on the surface of the mounting substrate 120 on the counter substrate 130 side. In a region corresponding to the display region 100A on the surface of the mounting substrate 120, as shown in FIG. are placed. In a region corresponding to the display region 100A on the surface of the mounting substrate 120, for example, a plurality of scan wirings 1022 are formed extending in a direction intersecting (for example, perpendicular to) the data wirings 1021, and are arranged in parallel with a pitch of The data wiring 1021 and the scan wiring 1022 are made of a conductive material such as Cu, for example.

The scan wiring 1022 is formed, for example, on the outermost layer, for example, on an insulating layer (not shown) formed on the base material surface. The base material of the mounting board 120 is made of, for example, a silicon substrate or a resin substrate, and the insulating layer on the base material is made of, for example, SiN, SiO, aluminum oxide (AlO), or a resin material. On the other hand, the data wiring 1021 is formed in a layer (for example, a layer below the outermost layer) different from the outermost layer including the scan wiring 1022, for example, formed in an insulating layer on the substrate. . On the surface of the insulating layer, in addition to the scan wiring 1022, for example, black is provided as necessary. Black is for enhancing contrast and is composed of a light-absorbing material. The black is formed, for example, at least on areas where

pad electrodes

1021B and 1022B, which will be described later, are not formed on the surface of the insulating layer. It should be noted that black can be omitted if necessary.

Display pixels P are formed in the vicinity of the intersections of the data lines 1021 and the scan lines 1022, and a plurality of display pixels P are arranged, for example, in a matrix in the display area 100A. Each display pixel P is mounted with a light-emitting unit 2 including a plurality of light-emitting devices 1 corresponding to, for example, RGB. In FIG. 21, one display pixel P is composed of three light emitting

devices

1R, 1G, and 1B, and red light is output from the light emitting device 1R, green light is output from the light emitting device 1G, and blue light is output from the light emitting device 1B. A case where it is possible to do so is exemplified.

The image display device 100 shown in FIG. 20 is an example of a passive matrix image display device. The light emitting device 1 of the present embodiment can be applied not only to a passive matrix image display device (image display device 100), but also to an active matrix image display device. Note that the active matrix image display device does not require the frame region 100B shown in FIG. 20, for example.

In the passive matrix drive system, increasing the number of scan wires shortens the time allocated to each light emitting device, so the injection current must be increased as the duty ratio decreases, resulting in a decrease in luminous efficiency and device life. There is fear. To avoid this, it is necessary to lower the maximum brightness setting value. In addition, due to problems such as voltage drop and signal delay due to wiring resistance and parasitic capacitance, in large screens with many scanning lines and high-definition image display devices, the screen is divided into multiple partial screens and passive matrix drive is used in parallel. , or a method of actively driving the light emitting device is adopted. Parallel passive matrix driving requires wiring to be pulled out to the back of each partial screen to connect the drive circuit, and the image signal must also be divided and parallelized according to each partial screen. This leads to an increase in circuit scale. On the other hand, in the active drive method, a signal voltage holding and voltage-current conversion circuit is provided for each pixel, so that the above-described screen division is not performed, or at least in a state where the number of divisions is small, and higher luminance than passive matrix driving is obtained. be able to.

FIG. 22 shows an example of a general active matrix driven pixel circuit. In the active matrix driving method, a switching transistor (Tr1), a driving transistor (Tr2), and a capacitive element (Cs) are provided for each display pixel P (light emitting

devices

1R, 1G, 1B, near intersections between data wiring 1021 and scanning wiring 1022). are provided respectively. In the active matrix driving method, a switching transistor is used as a switch to write Vsig to a capacitive element, and in addition, the driving transistor is used as a current source for current control by the potential difference of power supply (Vcc)-Vsig to current-modulate the light-emitting device.

The light emitting unit 2 is provided with a pair of terminal electrodes for each of the

light emitting devices

1R, 1G, and 1B, for example. One terminal electrode is electrically connected to, for example, the data wiring 1021 and is electrically connected to the other terminal electrode, for example, the scan wiring 1022 . For example, the terminal electrode is electrically connected to the pad electrode 1021B at the tip of the branch 1021A provided on the data line 1021. FIG. Also, for example, the terminal electrode is electrically connected to the pad electrode 1022B at the tip of the branch 1022A provided in the scan wiring 1022. FIG.

The

pad electrodes

1021B and 1022B are formed, for example, on the outermost layer, and are provided at the site where the light emitting unit 2 is mounted, for example, as shown in FIG. Here, the pad electrodes 121B and 122B are made of a conductive material such as Au (gold).

The mounting substrate 120 is further provided with, for example, a plurality of pillars (not shown) that regulate the distance between the mounting substrate 120 and the opposing substrate 130 . The struts may be provided in a region facing the display region 100A, or may be provided in a region facing the frame region 100B.

The counter substrate 130 is made of, for example, a glass substrate or a resin substrate. In the counter substrate 130, the surface on the side of the light emitting device 1 may be flat, but is preferably rough. The rough surface may be provided over the entire region facing the display region 100A, or may be provided only in the region facing the display pixels P. FIG. The rough surface has fine unevenness on which light emitted from the display pixels P enters. The unevenness of the rough surface can be produced by sandblasting, dry etching, or the like, for example.

The control circuit 140 drives each display pixel P (each light emitting unit 2) based on the video signal. The control circuit 140 includes, for example, a data driver that drives the data lines 1021 connected to the display pixels P and a scan driver that drives the scan lines 1022 connected to the display pixels P. FIG. For example, as shown in FIG. 20, the control circuit 140 may be provided separately from the display panel 110 and connected to the mounting substrate 120 via wiring, or may be mounted on the mounting substrate 120. may

(Application example 2)
FIG. 23 is a perspective view showing another configuration example (image display device 200) of an image display device using the light emitting device (for example, light emitting device 1) of the present disclosure. The image display device 200 is a so-called tiling display. The image display device 200 includes, for example, a display panel 210 and a control circuit 240 that controls driving of the display panel 210, as shown in FIG.

The display panel 210 is obtained by superimposing a mounting substrate 220 and a counter substrate 230 on each other. The surface of the counter substrate 230 serves as an image display surface, and has a display area in the central portion and a frame area as a non-display area around it (both not shown). The counter substrate 230 is arranged, for example, at a position facing the mounting substrate 220 with a predetermined gap therebetween. Note that the counter substrate 230 may be in contact with the top surface of the mounting substrate 220 .

FIG. 24 schematically shows an example of the configuration of the mounting substrate 220. As shown in FIG. For example, as shown in FIG. 24, the mounting board 220 is composed of a plurality of unit boards 250 laid out like tiles. Note that FIG. 24 shows an example in which the mounting substrate 220 is configured by nine unit substrates 250, but the number of unit substrates 250 may be ten or more, or may be eight or less.

25 shows an example of the configuration of the unit board 250. FIG. The unit substrate 250 has, for example, a plurality of light emitting devices 1 laid out like tiles and a supporting substrate 260 supporting each light emitting device 1 . Each unit board 250 further has a control board (not shown). The support substrate 260 is composed of, for example, a metal frame (metal plate) or a wiring board. When the support substrate 260 is configured by a wiring substrate, it can also serve as a control substrate. At this time, at least one of the support substrate 260 and the control substrate is electrically connected to each light emitting device 1 .

(Application example 3)
FIG. 26 shows the appearance of the transparent display 300. As shown in FIG. The transparent display 300 has, for example, a display section 310 , an operation section 311 and a housing 312 . The display unit 310 uses the light-emitting device of the present disclosure (for example, the light-emitting device 1). The transparent display 300 can display images and character information while the background of the display section 310 is transparent.

In the transparent display 300, a light-transmitting substrate is used as a mounting substrate. Each electrode provided in the light-emitting device 1 is formed using a conductive material having optical transparency, like the mounting substrate. Alternatively, each electrode has a structure that is difficult to see by narrowing the width of the wiring or thinning the thickness of the wiring. In addition, the transparent display 300 can perform black display by superimposing a liquid crystal layer having a driving circuit, for example, and can switch between transmission and black display by controlling the light distribution direction of the liquid crystal.

Although the present disclosure has been described above with reference to the embodiment, modified examples 1 to 13, and application examples, the present disclosure is not limited to the above-described embodiments, and various modifications are possible. For example, in the above embodiments and the like, an example using an LED chip having a mesa portion M as the light source unit 10 was shown, but the shape of the LED chip is not limited to this.

In addition, in the above embodiment and the like, an example using an LED chip using an inorganic semiconductor was shown as the light source unit 10, but the present invention is not limited to this. As the light source unit 10, for example, an LED (OLED) using an organic semiconductor or a semiconductor laser (Laser Diode: LD) can be used.

Furthermore, the light-emitting device (for example, the light-emitting device 1) shown in the above embodiments and the like can be used in smartphones, televisions, notebook PCs, AR/VR equipment, projectors, head-up displays, in addition to the application examples 1 to 3 described above. (HUD), smart watches and video walls, etc.

It should be noted that the effects described in this specification are merely examples and are not limited, and other effects may also occur.

Note that the present disclosure can also be configured as follows. According to the present technology having the following configuration, a plurality of wavelength conversion materials and a plurality of scattering particles for converting first light emitted from the light source unit into second light having different wavelength bands are added to the wavelength conversion layer in the light source unit. The absorption coefficient of the first light in the vicinity of the side surface (first surface) is made lower than the absorption coefficient of the first light in the vicinity of the light extraction surface (second surface). This reduces the absorptance of the excitation light in the vicinity of the light source. Therefore, it is possible to achieve both light extraction efficiency and reliability.
(1)
a light source unit having a light exit surface and emitting first light from the light exit surface;
The light source unit has a first surface arranged on the light emitting surface side of the light source unit and arranged to face the light emitting surface and a second surface opposite to the first surface, and the first surface A plurality of wavelength conversion materials and a plurality of scattering particles for converting light into second light having a different wavelength band, wherein the absorption coefficient of the first light in the vicinity of the first surface is equal to that of the second surface. A light emitting device, comprising: a wavelength converting layer having a lower absorption coefficient for said first light in its vicinity.
(2)
The wavelength conversion layer has a first region and a second region in order from the first surface side,
The light-emitting device according to (1), wherein the concentration of the plurality of scattering particles in the first region is lower than the concentration of the plurality of scattering particles in the second region.
(3)
The light-emitting device according to (2), wherein the first region does not include the plurality of scattering particles.
(4)
The wavelength conversion layer has a first region and a second region in order from the first surface side,
any one of (1) to (3), wherein the concentration of the plurality of wavelength conversion materials in the first region is lower than the concentration of the plurality of wavelength conversion materials in the second region; A light emitting device as described.
(5)
The light-emitting device according to any one of (2) to (4), wherein the first region extends toward the second surface so as to surround the second region. .
(6)
(2) to (5), wherein the wavelength conversion layer further has a region that does not contain the plurality of wavelength conversion materials and the plurality of scattering particles between the first region and the second region. A light emitting device according to any one of the preceding.
(7)
The wavelength conversion layer has a first region, a second region and a third region in order from the first surface side,
the first region does not contain the plurality of wavelength converting materials and contains only the plurality of scattering particles;
the second region does not contain the plurality of scattering particles and contains only the plurality of wavelength converting materials;
The light emitting device according to any one of (1) to (6), wherein the third region comprises the plurality of wavelength converting materials and the plurality of scattering particles.
(8)
The wavelength conversion layer has a first region, a second region and a third region in order from the first surface side,
the first region does not include the plurality of scattering particles and only includes a plurality of first wavelength converting materials;
said second region comprises said plurality of first wavelength converting materials and said plurality of scattering particles;
said third region comprises a plurality of second wavelength converting materials and said plurality of scattering particles;
The light emitting device according to any one of (1) to (6), wherein the first wavelength converting material has higher light resistance than the second wavelength converting material.
(9)
The light-emitting device according to (8), wherein the first wavelength conversion material is a cadmium-based quantum dot phosphor, and the second wavelength conversion material is a cadmium-free quantum dot phosphor.
(10)
The wavelength conversion layer has a first region and a second region in order from the first surface side,
The plurality of quantum dots contained in the first region and the second region are different from each other in material, composition, and core/shell structure. Any one of (1) to (9) above. luminous device.
(11)
The wavelength conversion layer according to any one of (1) to (10), wherein a light reflecting structure is formed on a side surface between the first surface and the second surface of the wavelength conversion layer. luminous device.
(12)
The light-emitting device according to (11), wherein the side surface is an inclined surface that spreads from the first surface toward the second surface.
(13)
The light-emitting device according to any one of (1) to (12), further comprising an uneven structure on the second surface of the wavelength conversion layer.
(14)
a first light source unit, a second light source unit, and a third light source unit that emit the first light as the light source units;
As the wavelength conversion layer, a first wavelength conversion layer arranged on the light exit surface side of the first light source section, and a second wavelength conversion layer arranged on the light exit surface side of the second light source section. and a third wavelength conversion layer disposed on the light emitting surface side of the third light source unit,
the first wavelength conversion layer converts the first light into red light;
the second wavelength conversion layer converts the first light into green light;
The light-emitting device according to any one of (1) to (13), wherein the third wavelength conversion layer transmits or converts the first light into blue light.
(15)
The light emission according to (14) above, further comprising a wavelength selective layer that selectively reflects the first light on at least the second surfaces of the first wavelength conversion layer and the second wavelength conversion layer. device.
(16)
The light emission according to (14) or (15), further comprising a light distribution control structure on the second surface of the first wavelength conversion layer, the second wavelength conversion layer, and the third wavelength conversion layer. device.
(17)
The light-emitting device according to (16) above, wherein the light distribution control structure is any one of a microlens array, a photonic crystal, a moth-eye structure, a nanoantenna, and a metamaterial.
(18)
a first light source unit, a second light source unit, and a third light source unit that emit the first light as the light source units;
As the wavelength conversion layer, a first wavelength conversion layer arranged on the light exit surface side of the first light source section, and a second wavelength conversion layer arranged on the light exit surface side of the second light source section. and a third wavelength conversion layer disposed on the light emitting surface side of the third light source unit,
The first wavelength conversion layer, the second wavelength conversion layer and the third wavelength conversion layer each convert the first light into white light,
a red filter that selectively transmits red light on the second surface of the first wavelength conversion layer;
a green filter that selectively transmits green light on the second surface of the second wavelength conversion layer;
The light-emitting device according to any one of (1) to (17), further comprising a blue filter that selectively transmits blue light on the second surface of the third wavelength conversion layer. .
(19)
The light emitting device according to any one of (1) to (18), wherein the light source is a blue light emitting diode or an ultraviolet light emitting diode.
(20)
Equipped with a light emitting device,
The light emitting device is
a light source unit having a light exit surface and emitting first light from the light exit surface;
The light source unit has a first surface arranged on the light emitting surface side of the light source unit and arranged to face the light emitting surface and a second surface opposite to the first surface, and the first surface A plurality of wavelength conversion materials and a plurality of scattering particles for converting light into second light having a different wavelength band, wherein the absorption coefficient of the first light in the vicinity of the first surface is equal to that of the second surface. and a wavelength conversion layer having a lower absorption coefficient than the first light in the vicinity thereof.

This application claims priority based on Japanese Patent Application No. 2021-185012 filed on November 12, 2021 at the Japan Patent Office, and the entire contents of this application are incorporated herein by reference. to refer to.

Depending on design requirements and other factors, those skilled in the art may conceive various modifications, combinations, subcombinations, and modifications that fall within the scope of the appended claims and their equivalents. It is understood that

Claims

a light source unit having a light exit surface and emitting first light from the light exit surface;
The light source unit has a first surface arranged on the light emitting surface side of the light source unit and arranged to face the light emitting surface and a second surface opposite to the first surface, and the first surface A plurality of wavelength conversion materials and a plurality of scattering particles for converting light into second light having a different wavelength band, wherein the absorption coefficient of the first light in the vicinity of the first surface is equal to that of the second surface. A light emitting device, comprising: a wavelength converting layer having a lower absorption coefficient for said first light in its vicinity.
The wavelength conversion layer has a first region and a second region in order from the first surface side,
2. The light emitting device of claim 1, wherein the concentration of said plurality of scattering particles in said first region is lower than the concentration of said plurality of scattering particles in said second region.
The light-emitting device according to claim 2, wherein said first region does not contain said plurality of scattering particles.
The wavelength conversion layer has a first region and a second region in order from the first surface side,
2. The light emitting device of Claim 1, wherein the concentration of the plurality of wavelength converting materials in the first region is lower than the concentration of the plurality of wavelength converting materials in the second region.
The light-emitting device according to claim 2, wherein the first region extends toward the second surface so as to surround the second region.
3. The light emitting device of claim 2, wherein the wavelength converting layer further comprises a region free of the plurality of wavelength converting materials and the plurality of scattering particles between the first region and the second region.
The wavelength conversion layer has a first region, a second region and a third region in order from the first surface side,
the first region does not contain the plurality of wavelength converting materials and contains only the plurality of scattering particles;
the second region does not contain the plurality of scattering particles and contains only the plurality of wavelength converting materials;
2. The light emitting device of Claim 1, wherein said third region comprises said plurality of wavelength converting materials and said plurality of scattering particles.
The wavelength conversion layer has a first region, a second region and a third region in order from the first surface side,
the first region does not include the plurality of scattering particles and only includes a plurality of first wavelength converting materials;
said second region comprises said plurality of first wavelength converting materials and said plurality of scattering particles;
said third region comprises a plurality of second wavelength converting materials and said plurality of scattering particles;
2. The light emitting device of Claim 1, wherein said first wavelength converting material has a higher light resistance than said second wavelength converting material.
The light-emitting device according to claim 8, wherein the first wavelength conversion material is a cadmium-based quantum dot phosphor, and the second wavelength conversion material is a cadmium-free quantum dot phosphor.
The wavelength conversion layer has a first region and a second region in order from the first surface side,
2. The light emitting device of Claim 1, wherein the plurality of quantum dots contained in the first region and the second region differ from each other in material, composition and core/shell structure.
The light-emitting device according to claim 1, wherein a light reflecting structure is formed on a side surface between said first surface and said second surface of said wavelength conversion layer.
The light-emitting device according to claim 11, wherein the side surface is an inclined surface that widens from the first surface toward the second surface.
The light-emitting device according to claim 1, further comprising an uneven structure on said second surface of said wavelength conversion layer.
a first light source unit, a second light source unit, and a third light source unit that emit the first light as the light source units;
As the wavelength conversion layer, a first wavelength conversion layer arranged on the light exit surface side of the first light source section, and a second wavelength conversion layer arranged on the light exit surface side of the second light source section. and a third wavelength conversion layer disposed on the light emitting surface side of the third light source unit,
the first wavelength conversion layer converts the first light into red light;
the second wavelength conversion layer converts the first light into green light;
2. The light emitting device of Claim 1, wherein said third wavelength converting layer transmits or converts said first light to blue light.
15. The light emitting device of Claim 14, further comprising a wavelength selective layer selectively reflecting said first light on said second surface of at least said first wavelength converting layer and said second wavelength converting layer. .
15. The light-emitting device according to claim 14, further comprising a light distribution control structure on said second surface of said first wavelength conversion layer, said second wavelength conversion layer and said third wavelength conversion layer.
17. The light-emitting device according to claim 16, wherein said light distribution control structure is one of a microlens array, a photonic crystal, a moth-eye structure, a nanoantenna and a metamaterial.
a first light source unit, a second light source unit, and a third light source unit that emit the first light as the light source units;
As the wavelength conversion layer, a first wavelength conversion layer arranged on the light exit surface side of the first light source section, and a second wavelength conversion layer arranged on the light exit surface side of the second light source section. and a third wavelength conversion layer disposed on the light emitting surface side of the third light source unit,
The first wavelength conversion layer, the second wavelength conversion layer and the third wavelength conversion layer each convert the first light into white light,
a red filter that selectively transmits red light on the second surface of the first wavelength conversion layer;
a green filter that selectively transmits green light on the second surface of the second wavelength conversion layer;
2. The light emitting device of Claim 1, further comprising a blue filter selectively transmitting blue light on said second side of said third wavelength converting layer.
The light emitting device according to claim 1, wherein the light source is a blue light emitting diode or an ultraviolet light emitting diode.
Equipped with a light emitting device,
The light emitting device is
a light source unit having a light exit surface and emitting first light from the light exit surface;
The light source unit has a first surface arranged on the light emitting surface side of the light source unit and arranged to face the light emitting surface and a second surface opposite to the first surface, and the first surface A plurality of wavelength conversion materials and a plurality of scattering particles for converting light into second light having a different wavelength band, wherein the absorption coefficient of the first light in the vicinity of the first surface is equal to that of the second surface. and a wavelength conversion layer having a lower absorption coefficient than the first light in the vicinity thereof.